I try to work quickly taking no more then 30 seconds between sets for everything besides my main lift for the day which is usually Bench, Squats, Deads, Cleans, Push Press something along those lines in those cases i usually go about 1-2 minutes rest. I find working quickly really burns the muscles and considering my goals are more geared towards building endurance strength and cutting up this works well for me.

Personally I've always rested about 3 min. between sets. If I'm just starting a cycle and going light I might only rest 2-2.5 min. though. Although in the past year or so I often do a type of superset to get out of the gym quicker by not resting bet. my last heavy set of one bodypart and the warmup of the next. I was thinking of trying the blood and guts routine for something different, but the one min. rest is the one thing I don't agree with, esp. for exercises like leg presses and squats, but then again I guess your only doing warmups and one heavy set.

I'm talking about every exercise i do, which as i'm only 14 and not allowed to use free weights yet, consists of just machines.

By intensity, i assume you mean weight? if that is the case, would you like me to write the different weights i use? i would just post them anyway, but it might not be necessary, making me look a bit silly. And it takes a lot of effort lol.

As for conditioning, i'm not sure what to say really; i don't know for sure, but i would think i'm about 17 percent BF, and i do 6 minutes of HIIT five times a week (counting 2 two minutes of warm up per session), and i feel pretty fit, which i guess stands to reason. Apart from that though, i don't really know what constitutes conditioning, i'm afraid.

Intensity is a measure of the load in terms of a percentage of your 1RM. i.e., if your 1RM on the Barbell Back Squat was 200lbs then performing it with 150lbs would be 75% intensity.

People use the word intensity as a subjective description for the perceived difficulty of your workout which won't be measured precisely and only use a rough RPE scale.

Some factors behind this equation of how much rest;
- Goal, neural workouts will require longer rest periods to allow for recovery between sets (more motor units being used and a higher expression of strength in your set).
- Muscle group, you will not necessarily 'need' the same amount of rest following a back exercise in comparison to a bicep only exercise
- Rep range, a set of 25 squats to failure has a different energy system demand than a set of 3 squats to failure
- Exercise, a straight legged deadlift is same as a leg curl, even if you put them both on hamstring day
- Unilateral/bilateral exercises
- Personal muscle fibre types. Those with a higher proportion of fast twitch fibres would do better with longer rest periods as a generalisation

There are more, this just gives you an idea. You could use some basic ideas to get you started and say rest periods are inversely correlated with the TUT and therefore shorter sets geared towards strength gains you would allow longer rest periods and high rep work geared towards hypertrophy or fat loss you will take shorter rest periods.

IMO...hypertrophy work (more reps less weight) 30-60 seconds. Power work (high weight low rep) 1 minute up to several minutes, since the idea is to move maximum weights, can't do that with a 30 sec rest

My goal as a natural bodybuilder is to improve constantly, and win my pro card, while making an increasing amount of people doubt that I'm natural ;)